Page 12 - Morphoanatomical investigations of cones and pollen in Cathaya argyrophylla Chung & Kuang (Pinaceae, Coniferales) under systematical and evolutional aspects

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V. M. Dörken and H. Nimsch Feddes Repertorium 2014, 125, 25–38

res as occuring e.g. in Taxus (Taxaceae) as derived lous microsporangiophores the central sporangia hardly
from a radial synangium consisting of several dorsiven- can be inserted lateral at the margin of a sporophyll.
tral reduced sporangiophores. Apart from normal micro- Among conifers the evolution of a dorsiventral bauplan
sporangiophores with two microsporangia the investi- of microsporangiophores might represent an optimiza-
gated Cathaya pollen-cones showed also micro- tion in respect to several functional aspects such as
sporangiophores with three sporangia. This is also protection of sporangia before anthesis and secondary
described for Picea asperata where sometimes micro- pollen exposition, both also realized in Cathaya. Fur-
sporangiophores with three or four sporangia have been thermore the dorsiventral bauplan allows a more dense
found (Mundry 2000). Such anomalies may lead to the arrangement of sporangiophores at the cone axis, than it
idea that microsporangiophores in Pinaceae represent a would be possible in perisporangiate cones (Mundry
reduced structure derived from a perisporangiate spo- 2000).
rangiophore as it could be shown for Torreya (Tax-
aceae). In studies on the character state evolution of We are grateful to Dr. Michael Laumann and Mrs.
Taxaceae pollen-cones (e.g. Wilde 1975; Mundry & Lauretta Nejedli (Electron Microscopy Center, Depart-
Mundry 2001; Dörken et al. 2011) a complete transition ment of Biology, University of Konstanz, Germany) for
line beginning with inflorescence-like cones in Cephalo- technical support (SEM and paraffin technique). Fur-
taxus and ending with flower-like cones in Taxus and thermore we thank Mr. Oliver St. John (Sheffield, Eng-
Torreya could be shown. Pollen-cones of Pseudotaxus land) for his great linguistic support. Furthermore we
with partly reduced pherophylls present an intermediate thank Prof. Dr. Th. Stützel (Ruhr-University Bochum,
link. In Taxaceae it could be shown that the perisporan- Bochum, Germany) for critical comments that helped to
giate microsporangiophores of Pseudotaxus, Taxus and improve the manuscript. We are also grateful to Prof. Dr.
the terminal synangium of Cephalotaxus are homolo- Reinhard Zetter (Department of Palaeontology, Univer-
gous structures. Accordingly, the perisporangiate micro- sity of Vienna, Austria) for discussing the pollen mor-
sporangiophores of Pseudotaxus and Taxus correspond phology.
to an entire lateral cone of Cephalotaxus, in which all
lateral hyposporangiate microsporangiophores got re-
duced. Pollen-cones of Taxus differ from Pseudotaxus 5 References
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